Umberto Zanovello, Carina Fuss, Alessandro Arduino, and Oriano Bottauscio, Magnetic Resonance in Medicine 2023, Volume 90, online 29 June 2023; doi: 10.1002/mrm.29787
This study, led by Istituto Nazionale di Ricerca Metrologica (INRIM) Turino, was supported by IT'IS as part of our participation in the "Standardization for safe implant scanning in MRI" (STASIS) project from the European Partnership on Metrology, co-financed from the European Union’s Horizon Europe Research and Innovation Programme and by the participating states. The purpose of the study is to propose an efficient numerical method to predict the temperature increase of an implantable medical device induced by any linearly polarized homogeneous magnetic field, according to the ISO 10974 methodology for testing of gradient-induced device heating. The concepts of device-specific power and temperature tensors are introduced to mathematically describe the electromagnetic and thermal anisotropic behavior of the device, from which the device heating for an arbitrary exposure direction can be predicted. The proposed method is compared to a brute-force approach based on simulations, and validated by applying it to 4 reference orthopaedic implants with a commercial simulation software. The results indicate that the proposed method requires about 5% of the time required by the brute-force approach, and 30% of the memory occupancy. The temperature increase predicted by the proposed method over a range of incident magnetic field exposures deviated from brute-force direct simulations by less than ±0.3%. We conclude that the proposed method allows one to efficiently predict the heating of an implantable medical device induced by any linearly polarized homogeneous magnetic field using a small fraction of the simulations required by the brute force approach. The results can be used to predict the worst-case orientation of the gradient field for subsequent experimental characterization according to the ISO 10974 standard.
The scientific and technical impact of the study can be summarized as: